// Problem.java
public abstract class Problem {
    protected String question;
    protected char correctAnswer;

    public Problem(String question, char correctAnswer) {
        this.question = question;
        this.correctAnswer = correctAnswer;
    }

    public abstract void display();

    public String getQuestion() {
        return question;
    }

    public char getCorrectAnswer() {
        return correctAnswer;
    }
}

